Fluctuating Vision Loss, Seizures, and Left Parieto-Occipital Mass
A 35-year-old man sought care for progressive visual disturbance. Magnetic resonance imaging of the brain showed a large, left-sided, parieto-occipital, contrast-enhancing lesion. He was treated with dexamethasone with brief improvement in vision. Within 5 days he had progressive vision worsening. Two weeks after the onset of his symptoms, brain magnetic resonance imaging showed a decrease in lesion size, and corticosteroids were discontinued. Two months after symptom onset he was found to have alexia without agraphia, and follow-up magnetic resonance imaging showed an increased size of the lesion. Two months after disease onset, the patient underwent a left occipital brain biopsy, which demonstrated a macrophage-enriched active demyelinating lesion with relative axonal sparing. Right arm weakness and aphasia developed, along with a fever. He was treated with dexamethasone. Electroencephalography indicated multiple seizures. Repeated cerebrospinal fluid analysis showed a slightly increased white blood cell count, increased protein level, immunoglobulin G index of 0.84, and the presence of 3 cerebrospinal fluid-unique oligoclonal bands. He was treated with 5 days of intravenous methylprednisolone and levetiracetam, with improvement. Three and a half years later, the patient came to the emergency department with weakness of the left leg associated with reduced sensation. Spinal magnetic resonance imaging showed a new demyelinating contrast-enhancing lesion from T2 to T7. He was treated with 5 days of intravenous methylprednisolone followed by 6 sessions of plasma exchange, with improvement. A diagnosis of relapsing tumefactive demyelination was made. The patient was subsequently treated with ocrelizumab. Tumefactive demyelinating lesions pose a diagnostic challenge, especially if they are the first manifestations of demyelinating disease. Typically, tumefactive demyelinating lesions are large (>2 cm) and are associated with edema, mass effect, and variable patterns of contrast enhancement.